Effect of hypoxia on electrical activity of atrioventricular nodal cells and atrial cells of the rabbit's heart.
The effect of hypoxia on the electrical activities of atrial cells and atrioventricular (AV) nodal cells (AN, N, NH) excised from the rabbit heart were examined. Within 5 minutes under a hypoxic condition, N cells and NH cells of the AV node responded in a 2:1 manner to electrical stimulation with a basic cycle length of 300 msec, but atrial cells and AN cells of the AV node responded in a 1:1 manner. Even after 120 minutes of hypoxia, atrial cells and AV nodal cells responded in a second-degree fashion to electrical stimulation with a basic cycle length of 300 msec. After 10 minutes, 60 minutes, and 120 minutes of hypoxia, shortest pacing basic cycle lengths with 1:1 responses to electrical stimulation increased significantly. AV nodal automaticity rate decreased significantly. AV nodal automaticity rate decreased significantly after 10 minutes and 120 minutes of hypoxia. After 120 minutes of hypoxia, reoxygenation for 30 minutes produced complete recovery of action potential characteristics in atrial cells but not in AV nodal cells.
Hirata
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First Department of Internal Medicine, Kumamoto University Medical School, Japan.
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001283:Atrioventricular Node / Q000166:cytology / Q000503:physiopathology*; D004562:Electrocardiography; D006325:Heart Atria / Q000166:cytology / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D011817:Rabbits; D013997:Time Factors